L-arginine/nitric oxide pathway activation in platelets of migraine patients with and without aura.

Nitric oxide (NO) in platelets has been proposed as a promising tool for studying NO variations in migraine. In the present research the platelet response to collagen and the basal and collagen-induced production of NO and cGMP in platelet cytosol were assessed in migraine patients (25 with aura and 35 without aura) both interictally and ictally, and compared with the same parameters in 30 age-matched control subjects. A reduced responsiveness to collagen was found in migraine patients, particularly those with aura, and this was more marked during attacks (ANOVA interictal periods: p < 0.01, attacks: p < 0.02) The basal and collagen-stimulated production of NO and cGMP in the platelet cytosol was significantly higher in migraine patients with aura assessed in interictal periods than in control subjects, and this production was further increased during attacks (interictal period: NO ANOVA: p < 0.001, ictal period: p < 0.01; cGMP: interictal period p < 0.01, ictal period: p < 0.02). The increase in platelet NO and cGMP production was also evident, though to a lesser extent, in migraine patients without aura. The present research supports the hypothesis of an activation of the L-arginine/NO pathway in migraine patients, especially those with aura, and confirms the findings of a previous study of increased levels of L-arginine in platelets of migraine patients studied in headache free-periods, and decreased collagen aggregation in whole blood.